1. Field of the Invention
The present invention relates to a humidifier for supplying moisture to any desired space such as the interior of a room and the like, thus raising the humidity, and relates in particular to a humidifier employing moisture-permeable polyurethane as a moisture-permeable membrane.
This application is based on Japanese Patent Applications, Nos. 2001-389560, 2002-208170, and 2002-370808, the contents of which are incorporated herein by reference.
2. Description of Related Art
GORE-TEX (registered trademark), a product comprised of polytetrafluoroethylene (PTFE) resin incorporating innumerable micropores, and polyurethane resin, are known as moisture-permeable resins used in conventional humidifiers. When polytetrafluoroethylene resin is employed, particularly as a fabric, it provides the opposing functions of being waterproof while at the same time being moisture-permeable in that it is impermeable to liquid water while being permeable to water vapor, and is therefore employed in a variety of clothing.
In recent years, the applications of materials having the functions of being waterproof while at the same time being moisture-permeable have expanded, and humidifiers wherein the aforementioned materials are employed to release only a preset amount of clean moisture (water vapor) are under investigation, and have been implemented in some cases.
The related art is disclosed in the documents hereunder.
Japanese Unexamined Patent Application, First Publication No. Hei 08-100935
Japanese Unexamined Patent Application, First Publication No. Sho 60-171337
Japanese Unexamined Patent Application, First Publication No. Sho 61-250429
In humidifiers employing the moisture-permeable resin formed from polytetrafluoroethylene resin, a hollow structure in the shape of a bag formed from layers of the moisture-permeable resin is filled with water, and water vapor is passed through the micropores formed in the moisture-permeable resin. However, it has been pointed out that various bacteria which reproduce both inside and outside the humidifier pass through the micropores with the water vapor and are dispersed in the air, resulting in problems of hygiene.
Furthermore, foreign matter such as calcium deposits and microscopic metal constituents (generally referred to as ‘scale’) and the like included in the water remain in the interior of the hollow structure, and tend to be gradually concentrated due to the structure of humidifiers wherein only water is evaporated and released. Therefore, the concentrated calcium deposits and foreign matter and the like tend to block the micropores with operation of the humidifier over a long period of time, and once the micropores are blocked, passage of the water vapor deteriorates and the performance of the humidifier deteriorates dramatically. In such cases, since the functions of the humidifier cannot be recovered unless the components employing the moisture-permeable resin are replaced, there is also a problem of the costs of maintenance. These costs increase due to the complex structure of the hollow structure, and are therefore comparatively high.
Moreover, conventional humidifiers require a heater to produce humidified air for the adjustment of humidity. However since considerable energy is consumed in driving a large-capacity heater to generate heat, it is not possible to satisfy consumer requirements in terms of energy-efficiency as desired by the market.